Influences of Pressureon the Operation of ReactiveDistillation Columns Involving Kinetically Controlled Exothermic Reactions.

For the reactive distillation column involving a kineticallycontrolledexothermic reaction, operating pressure can present nonmonotonic influenceson process dynamics and operation. While the enhancement of operatingpressure benefits process dynamics and controllability in the lowerpart of its feasible region (which is confined by the temperaturelevels of the available cold and hot utilities), it turns to deteriorateprocess dynamics and controllability in the higher part of its feasibleregion. Three reactive distillation systems, including an ideal reactivedistillation column performing a hypothetical exothermic reaction,A B ⇀↽kbkfC D, and two real ones producing, respectively,methyl acetate from acetic acid and methanol and methyl tertiary butylether (MTBE) from isobutylene and methanol, are thoroughly studiedin this work, and the results confirm the existence of this uniquephenomenon. The intricate behavior of such kind of reactive distillationcolumns is essentially governed by the conflicting effects of operatingpressure on reaction rate and chemical equilibrium constant and determinesactually a favorable region of operating pressure for process dynamicsand operation. Because the region may or may not coincide with theone in terms of process synthesis and design, operating pressure cantherefore serve as an important decision variable to trade-off processdesign and operation, rendering the resultant process design withbalanced steady-state performance and process dynamics and controllability. [ABSTRACT FROM AUTHOR]